JP2008290607A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire which can eliminate of defects in a strip piece cutting step and a splice step when steel cords are combined with organic fiber cords to form reinforcement cords of a belt layer. <P>SOLUTION: This pneumatic radial tire comprises at least one layer of belt layers 6A, 6B formed by joining the sides of a plurality of strip pieces formed by covering a plurality of reinforcement cords arranged parallel to each other with rubber to each other so that the reinforcement cords are tilted relative to the circumferential direction of the tire. The strip piece used is a strip piece SB formed by arranging organic fiber cords C2 at an inner portion while arranging steel cords C1 at both edges in the lateral direction of the strip. Preferably, the strip pieces SB formed by arranging the organic fiber cords C2 at the inner portion while arranging the steel cords C1 at both edges in the lateral direction of the strip and the strip pieces SA including only the steel cords C1 as the reinforcement cords are mixed in each single belt layer 6A, 6B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire provided with a belt layer composed of a plurality of strip pieces, and more specifically, in the case of using a combination of a steel cord and an organic fiber cord as a reinforcing cord for the belt layer, the strip piece The present invention relates to a pneumatic radial tire that can eliminate problems in the cutting process and the splicing process.

  In manufacturing technology for pneumatic radial tires, multiple strip pieces made of rubber coated multiple parallel reinforcing cords are butted against each other so that the reinforcing cords are inclined with respect to the tire circumferential direction. It has been proposed to form a belt layer having a desired dimension by joining together (see, for example, Patent Documents 1 to 3).

  In a pneumatic radial tire having such a structure, for example, by changing the cord angle of the belt layer, the in-plane rigidity and envelope characteristics of the belt layer are adjusted, and thereby required characteristics such as steering stability and riding comfort To be satisfied. However, when forming a belt layer composed of a plurality of strip pieces, a strip-shaped strip material formed by rubber coating a plurality of reinforcing cords arranged in parallel is bias-cut according to the cord angle of the belt layer, In general, a plurality of strip pieces which have been bias-cut are sequentially joined. Therefore, in order to change the cord angle of the belt layer, it is necessary to change the cutting angle of the strip-shaped strip material, and the changing work of the cutting device is a factor that hinders the productivity of the tire.

Therefore, without changing the cord angle of the belt layer, for example, a strip piece made of steel cord and a strip piece made of organic fiber cord are prepared, and the characteristics of the belt layer are adjusted by combining these two kinds of strip pieces. It is possible. However, the strip pieces made of steel cords and the strip pieces made of organic fiber cords have extremely different rigidity, so that problems easily occur in the cutting process and the splicing process of the strip pieces. In particular, since the strip piece made of the organic fiber cord has insufficient rigidity, the strip piece is bent when the cut strip piece is fed, and the bonding at the time of splicing becomes unstable. Therefore, in a pneumatic radial tire including a belt layer composed of a plurality of strip pieces, it is extremely difficult to use a steel cord and an organic fiber cord in combination as a reinforcing cord for the belt layer.
Japanese Patent Laid-Open No. 2005-153349 JP-A-2005-186325 Japanese Patent Laid-Open No. 2002-210841

  An object of the present invention is to provide a pneumatic radial tire that can eliminate problems in the strip cutting process and the splicing process when a steel cord and an organic fiber cord are used in combination as a reinforcing cord for a belt layer. There is to do.

  In order to achieve the above object, a pneumatic radial tire according to the present invention comprises a plurality of strip pieces formed by rubber coating a plurality of reinforcing cords arranged in parallel, and the reinforcing cords are inclined with respect to the tire circumferential direction. In a pneumatic radial tire having at least one belt layer formed by abutting the side portions and joining each other, steel cords are disposed at both edge portions in the strip width direction as the strip pieces. However, a strip piece in which an organic fiber cord is arranged on the inner part is used.

  In order to achieve the above object, a pneumatic radial tire according to the present invention includes a plurality of strip pieces formed by rubber-covering a plurality of reinforcing cords arranged in parallel, and the reinforcing cords extend in the tire circumferential direction. In a pneumatic radial tire having at least one belt layer formed by abutting side portions so as to be inclined and joined to each other, in a single belt layer, on both edge portions in the strip width direction A strip piece in which an organic fiber cord is arranged in an inner portion while arranging a steel cord and a strip piece including only a steel cord as a reinforcing cord are mixed.

  In the present invention, in a pneumatic radial tire including a belt layer composed of a plurality of strip pieces, when using a combination of a steel cord and an organic fiber cord as a reinforcing cord for the belt layer, both edge portions in the strip width direction are used. By using the strip piece in which the organic fiber cord is arranged in the inner portion while the steel cord is arranged in the strip, it is possible to sufficiently secure the rigidity of the strip piece including the organic fiber cord. Problems in the splicing process can be solved.

  In the present invention, the number of steel cords arranged in each outer portion of the strip piece including both the steel cord and the organic fiber cord is three or more in order to more surely eliminate the trouble in the cutting process and the splicing process of the strip piece. The number is preferably 5 or less.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic radial tire according to an embodiment of the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3, 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside of the tire to the outside. Two belt layers 6A and 6B are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 6A and 6B are disposed such that the reinforcing cords are inclined with respect to the tire circumferential direction and the reinforcing cords cross each other between the layers. Furthermore, if necessary, a belt cover layer formed by winding a reinforcing cord in the tire circumferential direction may be disposed on the outer peripheral side of the belt layers 6A and 6B.

  FIG. 2 is a plan view showing a strip piece including only a steel cord as a reinforcing cord, and FIG. 3 is an enlarged cross-sectional view taken along arrow X1-X1 in FIG. As shown in FIG. 2, a strip-shaped strip material SLA formed by rubber coating a plurality of steel cords C1 arranged in parallel is bias-cut so as to be inclined with respect to the width direction thereof, whereby a short strip piece is obtained. SA is processed. The twisted structure of the steel cord C1 is not particularly limited, and examples thereof include 1 × N (N = 2 to 6), 2 + N (N = 1 to 7), and the like.

  FIG. 4 is a plan view showing a strip piece including both a steel cord and an organic fiber cord as a reinforcing cord, and FIG. 5 is an enlarged cross-sectional view taken along arrow X2-X2 in FIG. As shown in FIG. 4, a bias cut is made so that a strip-shaped strip material SLB formed by rubber coating a plurality of steel cords C1 and a plurality of organic fiber cords C2 arranged in parallel is inclined with respect to the width direction. By doing so, the short strip piece SB is processed. In the strip piece SB, the steel cord C1 is selectively disposed on both edge portions P1, P3 in the strip width direction, and the organic fiber cord C2 is selectively disposed on the inner portion P2 in the strip width direction. The steel cord C1 of the strip piece SB is preferably the same type as the strip piece SA. On the other hand, examples of the organic fiber cord C2 include fiber cords such as nylon, polyethylene terephthalate (PET), polyolefin ketone (POK), and aramid. It is preferable that the outer diameter of the steel cord C1 and the outer diameter of the organic fiber cord C2 are substantially the same.

  FIG. 6 is a perspective view showing an extracted belt layer (6A) located inside the tire, and FIG. 7 is a perspective view showing an extracted belt layer (6B) located inside the tire. As shown in FIG. 6 and FIG. 7, the belt layers 6A and 6B have a plurality of strip pieces SA and SB each including a plurality of reinforcing cords, and side portions thereof are arranged so that the reinforcing cords are inclined with respect to the tire circumferential direction. And are joined together. In each of the belt layers 6A and 6B, a strip piece SA including only the steel cord C1 as a reinforcing cord, and a strip piece in which the organic fiber cord C2 is arranged on the inner side while the steel cord C1 is arranged on both edge portions in the strip width direction. They are arranged so that SB is mixed. The arrangement of the strip pieces SA and SB may be regular or random.

  In the pneumatic radial tire configured as described above, when the steel cord C1 and the organic fiber cord C2 are used in combination as the reinforcing cords of the belt layers 6A and 6B, the steel cord C1 is disposed at both edge portions in the strip width direction. However, since the strip piece SB in which the organic fiber cord C2 is disposed on the inner portion is used, the strip piece SB can have sufficient rigidity. As a result, the strip pieces SA and SB are cut and spliced. Can solve the problem. Of course, it is possible to set desired tire characteristics by appropriately combining the strip piece SA including only the steel cord C1 as the reinforcing cord and the strip piece SB including the steel cord C1 and the organic fiber cord C2.

  In the pneumatic radial tire described above, the number of steel cords C1 disposed in each of the outer portions P1 and P3 of the strip piece SB including both the steel cord C1 and the organic fiber cord C2 is preferably 3 or more and 5 or less. If the number of steel cords C1 in each of the outer portions P1 and P3 of the strip piece SB is less than 3, the effect of improving the feeding of the members in the cutting process and the bonding of the members in the splicing process becomes insufficient. Even beyond the book, no further effect can be expected.

  In the present invention, the strip piece SA including only the steel cord C1 as the reinforcing cord and the strip piece SB including the steel cord C1 and the organic fiber cord C2 can be combined in an arbitrary pattern. For example, two strip pieces SA and one strip piece SB are alternately arranged, one strip piece SA and one strip piece SB are alternately arranged, or one strip piece SA. And two strip pieces SB can be alternately arranged. Alternatively, the belt layer may be configured using only the strip piece SB including the steel cord C1 and the organic fiber cord C2 without using the strip piece SA including only the steel cord C1 as the reinforcing cord.

  The tire size is 225 / 40ZR18, and a plurality of strip pieces made by rubber-covering a plurality of reinforcing cords arranged in parallel are butted against each other so that the reinforcing cords are inclined with respect to the tire circumferential direction. In the pneumatic radial tire provided with the two belt layers formed by joining together, the tires of Examples 1 to 3 and Comparative Examples 1 and 2 in which the belt layers were formed using the strip pieces of Table 1 were used. Produced.

  In the tires of Examples 1 to 3, the strip piece SA including only the steel cord as a reinforcing cord in a single belt layer, and the organic fiber cord in the inner portion while arranging the steel cord at both edge portions in the strip width direction Are mixed with the strip piece SB on which are arranged. On the other hand, the tire of Comparative Example 1 is configured by forming a belt layer using a strip piece SA including only a steel cord as a reinforcing cord. In the tire of Comparative Example 2, a belt layer is formed using a strip piece containing only an organic fiber cord as a reinforcing cord.

  For the tires of Examples 1 to 3 and Comparative Examples 1 and 2, workability in the strip piece cutting step and the splicing step was evaluated by the following method, and the results are also shown in Table 1.

Workability in the cutting process:
In order to obtain each test tire, the strip piece was repeatedly cut, the state when the strip piece was fed out after cutting was visually confirmed, and the rate at which inconvenience such as bending occurred in the strip piece was examined. The evaluation results are shown as an index using Comparative Example 1 as 100, using the reciprocal of the measured value. It means that workability | operativity in a cutting process is excellent, so that this index value is large.

Workability in splicing process:
In order to obtain each test tire, splicing of the strip pieces was repeated, and the bonding state of the strip pieces was visually confirmed, and the rate at which inconvenience such as poor bonding occurred on the strip pieces was examined. The evaluation results are shown as an index using Comparative Example 1 as 100, using the reciprocal of the measured value. A larger index value means better workability in the splicing process.

  As is apparent from Table 1, the tires of Examples 1 to 3 are comparative examples using only steel cords, although steel cords and organic fiber cords are used in combination as reinforcing cords for the belt layer. Workability equivalent to 1 could be secured. On the other hand, as a result of using the tire cord of Comparative Example 2 in combination with the steel cord and the organic fiber cord as the reinforcing cord for the belt layer, the workability in the strip cutting process and the splicing process was deteriorated.

1 is a meridian half cross-sectional view showing a pneumatic radial tire according to an embodiment of the present invention. It is a top view which shows the strip piece which contains only a steel cord as a reinforcement cord. FIG. 3 is an enlarged cross-sectional view taken along arrow X1-X1 in FIG. 2. It is a top view which shows the strip piece containing both a steel cord and an organic fiber cord as a reinforcement cord. FIG. 5 is an enlarged cross-sectional view taken along arrow X2-X2 in FIG. 4. It is a perspective view which extracts and shows the belt layer (6A) located inside a tire. It is a perspective view which extracts and shows the belt layer (6B) located in a tire inner side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6A, 6B Belt layer C1 Steel cord C1 Organic fiber cord SA, SB Strip piece

Claims (3)

  It is formed by joining a plurality of strip pieces formed by rubber-covering a plurality of reinforcing cords arranged in parallel with each other butting the side portions so that the reinforcing cords are inclined with respect to the tire circumferential direction. Further, in the pneumatic radial tire provided with at least one belt layer, a strip piece in which an organic fiber cord is arranged in an inner portion while steel cords are arranged in both edge portions in the strip width direction is used as the strip piece. Pneumatic radial tire characterized by.   It is formed by joining a plurality of strip pieces formed by rubber-covering a plurality of reinforcing cords arranged in parallel with each other butting the side portions so that the reinforcing cords are inclined with respect to the tire circumferential direction. A pneumatic radial tire having at least one belt layer, a strip piece in which a single belt layer has steel cords arranged on both edge portions in the strip width direction and organic fiber cords arranged on an inner portion thereof. A pneumatic radial tire characterized by mixing a strip piece containing only a steel cord as a reinforcing cord.   3. The pneumatic radial tire according to claim 1, wherein the number of steel cords disposed on each outer portion of the strip piece including both the steel cord and the organic fiber cord is 3 or more and 5 or less.

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